The long term goal of these studies is to delineate the cellular and biochemical mechanisms by which tissue injury and infection lead to increased hepatic synthesis of the human acute phase protein, C-reactive protein (CRP), and to compare these mechanisms with those responsible for induction of other acute phase proteins. The specific aims of this proposal are to pursue and extend our finding that conditioned medium prepared from LPS-activated human monocytes in the presence of dexamethasone, and lacking demonstrable I1-1, induces increased synthesis of CRP in two human hepatoma cell line Employing the human Hep 3B cell line as a test system, we will characterize the metabolic requirements for release of CRP inducing activity from monocytes, determine the optimal dose of LPS required for CRP inducing activity release, and determine whether a particulate monocyte activator, latex beads, is equally capable of stimulating CRP inducing activity. The kinetics of release of CRP inducing activity by monocytes following stimulation will be determined. In all of the preceding studies, parallel observations of effect on synthesis of the other acute phase proteins SAA, alpha-1 antitrypsin, and alpha-1 antichymotrypsin will be made. We will determine accumulation and rate of transcription of the mRNA for these acute phase proteins following stimulation in vitro of Hep 3B cells to determine to what extent transcriptional or post- transcriptional mechanisms are responsible for increased synthesis of these proteins, and compare findings with parallel studies of rabbit acute phase proteins following in vivo stimulation. We will characterize the CRP inducing monokine (or monokines) by defining its molecular size, charge, stability following temperature change and on storage and sensitivity to trypsin, and determine whether this activity can be abolished by antibodies to I1-1. We will attempt to purify the CRP inducing monokine, so that amino acid composition and sequence can be determined and antibodies raised. The serum concentrations of these proteins are markedly elevated in a number of acute and chronic inflammatory diseases, and following many forms of tissue injury. These studies bear on the basic biologic process of the organism's response to tissue injury and infection and are relevant to many diseases, including chronic autoimmune disorders. They are also relevant to the pathogenesis of amyloidosis; SAA is the precursor of secondary amyloid fibrils, and CRP bears close homology to SAP, a constituent of all types of amyloid tissue and a murine acute phase protein.